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<p>In this study, plasma arc additive manufacturing (PAAM) was employed to fabricate Inconel 718 deposition specimens, and their microstructure and corrosion properties were investigated in the as-deposited and various heat-treated states. The as-printed (ASP) condition exhibited a typical dendritic structure with pronounced intergranular Laves phase segregation, strong &lt; 100 &gt; texture, and coarse grains. After high-temperature homogenization, the Laves phase was effectively eliminated in the homogenized (HOM) specimens, accompanied by significant recrystallization. The &lt; 100 &gt; texture intensity decreased from 34.81 to 19.32, the average grain size was refined from 207.2 to 103.18&#xa0;μm, and the microhardness decreased from 267.6 to 211.5 HV<sub>0.2</sub>. In contrast, the homogenization + solution-aging (HSA) specimens exhibited needle-like <i>δ</i> phase precipitation along grain boundaries, with &lt; 100 &gt; texture intensity increasing to 30.71 and grain size coarsening to 183.67&#xa0;μm. The precipitation of <i>γ</i>″/<i>γ</i>′ strengthening phases led to a substantial increase in microhardness to 447.9&#xa0;HV<sub>0.2</sub>. Electrochemical tests in 3.5&#xa0;wt.% NaCl solution revealed that ASP specimens had the poorest corrosion resistance, with a corrosion current density (Icorr) of 2.537 × 10<sup>−8</sup>&#xa0;A&#xa0;cm<sup>−2</sup> and a charge-transfer resistance (Rct) of 2.589 × 106&#xa0;Ω&#xa0;cm<sup>2</sup>. Heat treatment markedly improved corrosion resistance, with HSA specimens showing the best performance (Icorr = 4.983 × 10<sup>−9</sup>&#xa0;A&#xa0;cm<sup>−2</sup>, Rct = 2.657 × 106&#xa0;Ω&#xa0;cm2). Therefore, post-deposition heat treatments can significantly enhance the corrosion resistance of PAAM-Inconel 718 alloys.</p>

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Effects of Different Heat Treatment Processes on Microstructure and Corrosion Resistance of PAAM-Inconel 718 Alloy

  • 期刊论文

  • 发表日期：

    2026年2月8日

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  • Zhanfang Wang,
  • Houchao Chi,
  • Chuanguang Qin,
  • Ben Niu,
  • Bo Jiang,
  • Jilin Li,
  • Shiyi Gao

摘要

In this study, plasma arc additive manufacturing (PAAM) was employed to fabricate Inconel 718 deposition specimens, and their microstructure and corrosion properties were investigated in the as-deposited and various heat-treated states. The as-printed (ASP) condition exhibited a typical dendritic structure with pronounced intergranular Laves phase segregation, strong < 100 > texture, and coarse grains. After high-temperature homogenization, the Laves phase was effectively eliminated in the homogenized (HOM) specimens, accompanied by significant recrystallization. The < 100 > texture intensity decreased from 34.81 to 19.32, the average grain size was refined from 207.2 to 103.18 μm, and the microhardness decreased from 267.6 to 211.5 HV0.2. In contrast, the homogenization + solution-aging (HSA) specimens exhibited needle-like δ phase precipitation along grain boundaries, with < 100 > texture intensity increasing to 30.71 and grain size coarsening to 183.67 μm. The precipitation of γ″/γ′ strengthening phases led to a substantial increase in microhardness to 447.9 HV0.2. Electrochemical tests in 3.5 wt.% NaCl solution revealed that ASP specimens had the poorest corrosion resistance, with a corrosion current density (Icorr) of 2.537 × 10−8 A cm−2 and a charge-transfer resistance (Rct) of 2.589 × 106 Ω cm2. Heat treatment markedly improved corrosion resistance, with HSA specimens showing the best performance (Icorr = 4.983 × 10−9 A cm−2, Rct = 2.657 × 106 Ω cm2). Therefore, post-deposition heat treatments can significantly enhance the corrosion resistance of PAAM-Inconel 718 alloys.